Rhode island butt problem!!!!!

Help my year and a half year old Rhode island has a butt problem. She is very large in the rear end/ vent area. I treated her 2 weeks ago with warm water bathes and she seemed fine. She passed poop and liquid. Also passed an egg with no shell. Is still very active and eating and drinking. Today she is standing with her feathers low and rear end leaning towards the ground. But her in a warm bath and white liquid seeped out. What is wrong with her??? Would appreciate any suggestions